Method of producing a stable sodium perbor silicate composition



United States Patent METHOD OF PRODUCING A STABLE SODIUM PERBOR SILICATE COMPOSITION Harlow G. Hyatt, Williamsville, N.Y., assignor to Food Machinery and Chemical Corporation, New York, N.Y., a corporation of Delaware No Drawing.- Filed June 18, 1959, Ser. No. 821,323

2 Claims. (Cl. 252-99) This invention pertains to a method of producing an active oxygen containing detergent composition, and to such a composition. It pertains more particularly to a method of producing a detergent composition having wetting, detergent and bleaching properties, and to such a composition.

This application is a continuation-in-part of application Serial Number 575,341, filed April 2, 1956 in the name of the present inventor, which is a continuation-in-part of Serial No. 215,853, filed March 15, 1951, both now abandoned.

Detergent compositions having wetting, detergent and bleaching properties are of particular value in various laundry operations. Detergent compositions having wetting and detergent properties are commonly composed of natural and/ or synthetic soaps, surface active agents, and the like. If it be desired to impart bleaching properties to such a composition, a suitable bleaching agent, preferably of the active oxygen type, must be incorporated in the composition. Most bleaching agents of the active oxygen type, such as hydrogen peroxide itself, as well as its derivatives or addition products, such as sodium carbonate peroxide, sodium pyrophosphate peroxide, urea peroxide, sodium perborate, and other similar active oxygen compounds, when incorporated in a detergent composition, do not produce compositions of good bleaching activity because of their lack of stability in intimate mixture with the wetting and detergent components of the detergent composition.

Of the various bleaching agents of the active oxygen type, only sodium perbor silicate is fully compatible with the detergent and wetting components of detergent compositions, as its stability is not adversely afiected by intimate contact with natural and/or synthetic soaps, surface active agents and the like, commonly used in the manufacture of detergent compositions for laundry purposes.

Sodium perbor silicate may be manufactured in a mad ner fully described in US. Patent No. 2,367,971. This method of manufacture is, however, not well suited for the large scale production of an active oxygen containing detergent composition having wetting detergent, and bleaching properties.

Detergent compositions having only wetting and detergent properties are commonly produced in a single step method by spray-drying a solution containing all the desired components of the finished product. Spray-drying of such a solution will directly produce a fine, granular powder suitable for packaging without any further processing. Incorporation of sodium perbor silicate, produced in accordance with US. Patent No. 2,367,971, into such a detergent composition, to provide bleaching properties thereto, would require grinding and blending it with the powder obtained by spray-drying a solution containing the wetting and detergent components of the finished composition. This is possible to do, as pointed out in the above mentioned patent, but represents a procedure undesirable from the viewpoint of the detergent 2,955,086 1 Patented Oct. 4, 1960 manufacturer. For this reason, sodium perbor silicate, in spite of its many excellent properties, has not found acceptance as the bleaching component in detergent compositions.

It is an object of this invention to provide a novel method of producing sodium perbor silicate by spraydrying.

It is a further object of this invention to provide a novel method of producing a detergent composition having wetting, detergent, and bleaching properties by spraydrying a homogeneous solution of all its components, and to provide compositions of sodium perbor silicate havin unique properties.

I have found that sodium perbor silicate may be produced by spray-drying, if steps are taken to prevent the solution containing the starting materials; sodium hydroxide, sodium silicate, borax and hydrogen peroxide, from becoming gelatinous. Such gelatinization or solidification will invariably take place if the teaching of US. Patent No. 2,367,971 is followed. Gelatinization will, of course, make it impossible to process the solution by spray-drying, as the gelatinizing material would clog up and foul the delicate spraying mechanisms employed.

Gelatinization of the solution used in the manufacture of sodium perbor silicate can, however, be avoided safely, in accordance with the present invention, if provision is made to have present in that solution, sodium oxide Na O and silicon dioxide SiO in the ratio of substantially 1:1 to 121.2. A solution containing, aside from borax and hydrogen peroxide, sodium silicate and sodium hydroxide, in amounts corresponding to the above mentioned Na O to Si0 ratio, will not gelatinize and the solution may be spray-dried to produce a stable, yet freeilowing, fine granular powder ready for packaging, without further processing.

' If in the process of my invention, sodium silicate 42 Baum with a N320 to Si0 ratio of approximately 1:25 is used together with the amount of Na O introduced by the prescribed amount of sodium hydroxide 38 Baum, the b121 0 and :SiO will then be present in the solution to be spray-dried in a ratio of approximately 1:1.13.

Substantial deviation from this Na O to SiO ratio will change, in an undesirable manner, the properties of the solution and the properties of the spray-dried product obtained from that solution. If the ratio is changed in the direction of higher SiO content, the solution will gelatinize and thus become impossible to spray-dry. For example, a solution with a Na O to SiO ratio of 1:3 will gelatinize quite rapidly. On the other hand, a solution containing substantially less SiO than corresponds to a Na O to SiO ratio of about 1': 1.13 will remain fluid but, upon spray-drying, produces an end product of reduced stability. p 7

I, therefore, prefer to provide for an Na O to SiO ratio substantially between 1:1 to 1 1.2.

The following example will serve to illustrate how the process of my invention may be carried out, but is not given as limitative, as variations in amountof materials employed are permitted over a wide range as hereinafter indicated. 7

Example 1 In a mixing tank constructed of material compatible with hydrogen peroxide and the alkalies used, in this case a tank made of stainless steel, were placed in the order given:

sodium silicate 42 Baum After these materials had dissolved, about 17 lbs. of hydrogen peroxide 50% were added slowly and with stirring. The solution remained fluid and was not gelatin- Then the solution was fed to a spray-dryer and there processed in the customary manner to a free-flowing, dry powder, suitable for packaging without further processing. The finished product contained 6% active oxygen. It difiered from the perbor silicate of US. Patent No. 2,367,971 in that the latter contained different proportions of Components, and therefore had different properties. Only the chemical compositions of this invention, having the described ratio of Na O to SiO can be spray-dried to provide the unique perbor silicate products, and the unique detergent compositions containing them, of this invention. These products and detergent compositions have a combination of stability, combined with free-flowability, not found in perbor silicates having chemical compositions outside the present range of compositions.

Certain variations in the composition of the solution to be spray-dried are possible; Thus, if it is desired to produce a product containing only 3% active oxygen, the

oxide.

My invention also permits the production of a detergent composition having wetting, detergent and bleaching properties, by spray-drying a homogeneous solution containing not only the sodium silicate, sodium hydroxide, borax and hydrogen peroxide required to form sodium perbor silicate, but also additional surface active wetting and/or detergent agents, such as fatty acid soaps, synthetic detergents and the like. Such a procedure is illushated by the following example.

Example 2 In a mixing tank constructed of material compatible with hydrogen peroxide and the alkalies used, in this case a tank made of ceramic material, were first placed about 800 lbs. of water. Such a relatively large quantity of water is required to provide enough solvent to dissolve the amount of synthetic detergent used in this example. 'Ilhen were added, with stirring, and in the order given:

About 42 lbs. of sodium silicate 42 (Na,O:SiO 1 :2.5

Baum

It is to be understood that in place of the alkyl aryl sodium sulfonate used in this example, other surface active agents having the desired wetting and detergent properties may be added. Thesernay be, for example, ordinary fatty acid soaps, fatty alkyl sulfates, fatty monoglyceride sulfates, carboxy methyl cellulose, polyethylene oxide based non-ionic detergents, or other materials commonly used or desired to use in detergent compositions because of their special Wetting or detergent properties. Moreover, these materials may be added singly or in combination. 3

Thus it will be seen, that my invention permits to produce, by means commonly employed in the manufacture of powdered detergent compositions, namely, by spraydrying, detergent compositions having wetting and detergent properties based on any one or any combination of commonly used components with wetting 'and/ or detergent properties; and bleaching as, well as additional detergent properties based on sodium perbor silicate as an alkaline active oxygen containing component.

Preparation of the sodium perbor silicate in a separate step "and the various grinding and blending operations necessitated thereby, are thus avoided and production of the finished product ready for packaging, is achieved in one single step. It will also be understood that a. solution of caustic soda and hydrogen peroxide may be obtained by dissolving sodium peroxide in water, and the employment of such a solution is contemplated as within the scope of the invention and the claims appended hereto.

What is claimed is;

V 1. Method of producing a stable, active-oxygen containing, powdered sodium perbor silicate composition, comprising spray-drying a homogeneous free-flowing aqueous solution containing, in the indicated amounts by weight, about 4-8 parts of sodium hydroxide, about 40- 50 parts of sodium silicate having a degree Baum value of 42 and an Na O:SiO ratio of about 1:25, about 30 parts of borax, and at least about 4.parts of hydrogen peroxide, and in which composition the total Na O:SiO ratio is about 1:1 to 121.2.

2. Method of producing a stable, active-oxygen-containing, powdered sodium perbor silicate composition,

comprising spray-drying a homogeneous freeflowing aqueous solution containing, in the indicated amounts by weight, about 4-8 parts of sodium hydroxide, about 40 parts of sodium silicate having a degree Baum value p of 42 and an Na O:SiO ratio of about 112.5, about 30 About 21 lbs. of sodium hydroxide 38 Baum (32% NaOH) About 31 lbs. of borax, solid About 200 lbs. of an alkyl aryl sodium sulfonate parts of borax, and about 4-8.5 parts of hydrogen peroxide, and in which composition the total Na O:SiO, ratio is about 1:1 to 1:12.

References Cited in the file of this patent UNITED STATES PATENTS 2,185,632 Hill et a1. Ian. 2, 1940 2,243,054 Vail May 20, 1941 2,367,971 Spiegler I an. 23, 1945 2,423,451 Holuba July 8, 1947 2,491,789 Young Dec. 20, 1949 2,679,483 Armstrong et al May 25, 1954 2,738,365 Sylvester Mar. 13, 1956 2,868,615 Bell Ian. 13, 1959 

1. METHOD OF PRODUCING A STABLE, ACTIVE-OXYGEN CONTAINING, POWDERED SODIUM PERBOR SILICATE COMPOSITION, COMPRISING SPRAY-DRYING A HOMOGENEOUS FREE-FLOWING AQUEOUS SOLUTION CONTAINING, IN THE INDICATED AMOUNTS BY WEIGHT ABOUT 4-8 PARTS OF SODIUM HYDROXIDE, ABOUT 4050 PARTS OF SODIUM SILICATE HAVING A DEGREE BAUME VALUE OF 42* AND AN NA2O:SIO2 RATIO OF ABOUT 1:2.5. ABOUT 30 PARTS OF BORAX, AND AT LEAST ABOUT 4 PARTS OF HYDROGEN PEROXIDE, AND IN WHICH COMPOSITION THE TOTAL NA2O:SIO2 RATIOA IS ABOUT 1:1 TO 1:1.2. 